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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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16th Feb 2020, 6:46 pm | #1 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Battery valve set
Hi I'm trying to find out if the valve set up would work the same as on the service manual, the marconi I think is a osram kt2 but has no markings the valves are what was in the radio when I got it
The valve 1 = detector is dead so this will have to be replaced. if anyone has one they want to sale please let me know Mark |
16th Feb 2020, 7:32 pm | #2 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Battery valve set
We would need the circuit to help as this will define the bias conditions. You appear to have 2 output valves PM2 and KT2 so you probably need valves for V1 and V2. I presume 'dead' means the filament is open circuit?
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16th Feb 2020, 7:37 pm | #3 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,875
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Re: Battery valve set
I'm guessing this is for the KB New Pup 362 in a previous post
Cheers Mike T
__________________
Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
16th Feb 2020, 7:50 pm | #4 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Re: Battery valve set
Yes Colbert for the pup dave check the valves on his tester for me no markings on the marconi one so don't know what it is
Mark |
16th Feb 2020, 8:42 pm | #5 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
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Re: Battery valve set
OK, found the thread. In your original picture the PM2 is in the V2 position and that would definitely be wrong. The Pup has no bias supply for V1 and V2 (not quite true as it is connected to the -ve filament supply) so it is important to use valves, like the PM1HL, that are designed to work under this bias condition.
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16th Feb 2020, 9:05 pm | #6 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Re: Battery valve set
PJL in the manual valves 1 and 2 are the same in not sure on what's the difference between pm1 hl and pm2 hl.
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16th Feb 2020, 9:56 pm | #7 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Battery valve set
You need to look at the valve characteristics in the datasheets to understand why:
PM1HL http://g3ynh.info/valves/old/Data-Bo...G/MVG-p009.pdf This valve is described as a detector. PM2 http://g3ynh.info/valves/old/Data-Bo...G/RVG-p011.pdf This valve is described as an output valve. V2 has an anode feed resistor of 150,000 ohms. Assuming the design was intended to drop a maximum of 50V across the anode feed then the anode current must be less than 0.33mA when the grid voltage is zero. Now look at the characteristic chart for the PM1HL and you can see that with grid=0V and Ia=0.5mA the anode would be about 50V and that sounds reasonable. Do the same for the PM2 and the anode voltage would be next to nothing. A PM2HL should be OK as it is intended to be a direct replacement for a PM1HL, but the valve in the picture appears to be marked PM2. Trying the PM2 will do no harm as the 150,000 will prevent damage but I would expect it to perform very badly. Last edited by PJL; 16th Feb 2020 at 10:05 pm. |
16th Feb 2020, 10:07 pm | #8 |
Pentode
Join Date: Aug 2005
Location: North Warwickshire, UK.
Posts: 108
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Re: Battery valve set
Hi Rockingmark, yes you are correct. regarding the first two valves. Your paperwork shows that valve No1 and valve No2 should be PM1 -HL or equivalents and the valve No3 should be a PM22A or equivalent. If you try to purchase these valves just ask for PM1-HL or equivalent. Have you got any documentation with your radio to show where the valves should be installed in the set. Regards Brian
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16th Feb 2020, 10:09 pm | #9 |
Nonode
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 2,386
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Re: Battery valve set
Hi Mark, you might be in luck. My listings show the following used valves:
One KT2 One PM1HL One PM2HL One Pen220A Tomorrow I will test them for you on the VCM163 and let you know if they are any good. The weather here is vile so not going out to the garage tonight! Cheers, Jerry |
16th Feb 2020, 10:46 pm | #10 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Re: Battery valve set
Hi Jerry yeah it's very wet and windy down here as well. It would be great if you have them. When you get time there's no rush if you PM me the cost
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16th Feb 2020, 10:58 pm | #11 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Re: Battery valve set
Hi PJL thats what I was not sure of, the amplifier valve 2 is a pm2 it looks like I have to change them all. Thanks
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16th Feb 2020, 11:58 pm | #12 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
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Re: Battery valve set
The PM1HL and PM2HL offered by Jerry are perfect for V1 & V2.
You can use the PM2 as V3 (output valve) but it requires a larger grid voltage of say -10V. If the Marconi valve is a KT2 it should have 5 pins and should work as the set claims to be wired for pentodes and it claims to be an equivalent to the 220HPT. I would avoid the PEN220A offered by Jerry as it is considerably more powerful than the PEN220 and might possibly damage the output transformer. |
17th Feb 2020, 11:30 am | #13 |
Nonode
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 2,386
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Re: Battery valve set
Morning all; weather slightly better here so had a good rummage in the spares box; sorry, my list was out of date but I found one other contender (210HF) from your list. I've not bothered with the Pen220A based on PJL's advice: Here are the test results (spec values for a brand new valve in brackets):
KT2 - zero emission - scrapped PM1HL - not found PM2HL - Had a PM2A inside the box (Ia=7.6mA (5) gm=2.4mA/v (2)) 210HF Ia=2.6mA (1.6) gm=1.1mA/v (1.5) metallised Very sorry to build up false hopes - you have a PM re: 210HF. Assume you won't want the PM2A as it is a triode and you need a pentode for V3 (unless your KT2 works). Cheers, Jerry Last edited by cathoderay57; 17th Feb 2020 at 11:53 am. |
17th Feb 2020, 12:26 pm | #14 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Battery valve set
The PM2A is another output valve but you already have two. V3 appears to be wired for both triode (B4) and pentode (B5).
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17th Feb 2020, 12:27 pm | #15 |
Pentode
Join Date: May 2017
Location: Ware, Hertfordshire, UK.
Posts: 215
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Re: Battery valve set
hello all,, the reason mark came to my place was he was having trouble
testing resistors, so he came with the complete set (not much point with just a resistor) the problem his meter is rubbish !! reads some resistors some times ..so we changed two that were twice original value there are others that have gone high but should work (mark will change them later) the valves ,, Hl2 dead (no heaters)pm2 tested good ,wrong application but we thought it may sort off work. the Osram I tested as a pt2 its ok (if it is a pt2 ?)with an hl2 from my trf as first valve, no stations but loud noise from speaker when touching grid second valve.. so I think mark needs valve 1and 2 dave |
17th Feb 2020, 4:38 pm | #16 |
Octode
Join Date: Apr 2019
Location: Margate, Kent, UK.
Posts: 1,728
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Re: Battery valve set
Mark just stumbled on your thread I have a brand NOS marconi HL2 never used as I bought it for a battery receiver I had but never got round to using it.
I'm happy to sell on to you if happy with price. Here are some pics. Chris |
17th Feb 2020, 7:09 pm | #17 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Re: Battery valve set
Thanks dave for all you help and glad that I now know my meter was rubbish and not my mind I have ordered some resistors. Just thinking there is not much left inside that's original but I'm enjoying the hobby and learning a lot from everyone as I go
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17th Feb 2020, 8:25 pm | #18 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Re: Battery valve set
Thanks jerry (cathoderay57) shame about the rest of valves but at least that's one just one more to get
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